Sputtering System with a Plurality of Cathode Assemblies

ABSTRACT

A magnetron sputtering system includes a substrate mounted within a vacuum chamber. A plurality of cathode assemblies includes a first set of cathode assemblies and a second set of cathode assemblies, and is configured for reactive sputtering. Each cathode assembly includes a target comprising sputterable material and has an at least partially exposed planar sputtering surface. A target support is configured to support the target in the vacuum chamber and rotate the target relative to the vacuum chamber about a target axis. A magnetic field source includes a magnet array. A cathode assemblies controller assembly is operative to actuate the first set of cathode assemblies without actuating the second set of cathode assemblies, and to actuate the second set of cathode assemblies without actuating the first set of cathode assemblies.

FIELD OF THE INVENTION

The inventive subject matter disclosed herein involves a cathodeassembly for a sputtering system, and in particular, a cathode assemblyhaving a movable target. The inventive subject matter further involvessputtering systems including a plurality of cathode assemblies withmovable targets that may be operated in alternating fashion.

BACKGROUND

A sputtering process deposits a thin film of target material on asubstrate by dislodging small particles or atoms from a target, whichcoat the substrate. Magnetic fields have been used to enhance thesputtering process. For example, as disclosed in U.S. Pat. No. 4,166,018to Chapin, titled “Sputtering Process and Apparatus,” which isincorporated herein by reference in its entirety, in a conventionalvacuum sputtering process a substrate is placed in front of a sputteringcathode in a vacuum chamber. The sputtering cathode includes asubstantially planar target formed of the target material. The pressurein the chamber is reduced and then, optionally, back filled with areactive or inert sputtering gas or a combination of the two. A negativevoltage is applied to produce a plasma discharge at the target surface.The plasma discharge is intensified by magnets located behind the targetto produce a closed loop magnetic field over the target surface.

Over time, the target becomes depleted. Unfortunately, uneven depletionof the target, e.g., grooving of the target surface, can adverselyimpact the quality of the film deposited on the substrate as well aschange the uniformity of the film. It can also result in inefficient useof the target, with consequent cost penalties. One cause of unevendepletion of the target surface is that erosion is highest at regionswhere the magnetic field lines are tangent to the target surface. Thus,it is known in the art to rotate an array of magnets behind the target,to develop more uniform erosion of the target surface. U.S. Pat. No.4,995,958 to Anderson et al., titled “Sputtering Apparatus with aRotating Magnet Array having a Geometry for Specified Target ErosionProfile,” U.S. Pat. No. 5,248,402 to Ballentine et al., titled“Apple-Shaped Magnetron for Sputtering System,” U.S. Pat. No. 5,830,327to Kolenkow, titled “Methods and Apparatus for Sputtering with RotatingMagnet Sputter Sources,” and U.S. Pat. No. 6,258,217 to Richards et al.,titled “Rotating Magnet Array and Sputter Source,” each of which isincorporated herein by reference in its entirety, disclose variouscathode assemblies for sputtering systems having a magnet array thatrotates behind the plane of a circular flat target. It is also known tooptimize the shape of the magnet array, either symmetric or asymmetricwith respect to the axis of rotation, to further reduce uneven erosionof target surface.

A DC magnetron sputtering device with a plurality of cathode assembliesis disclosed in U.S. Pat. No. 9,771,647, titled “Cathode Assemblies andSputtering Systems”, which is incorporated herein by reference in itsentirety.

Rotating magnet arrays create a moving deposition erosion zone at thestationary surface of the target and, correspondingly, a movingdeposition plume from the surface of the target. This may result in anuneven deposition pattern on the substrate and a reduced ability todeposit precision films. This may be particularly problematic forcertain sputtering processes, such as long-throw sputtering orlong-throw reactive sputtering.

Further, the areas on the target that are not being eroded are subjectto back coating and reactive gas poisoning. This can result in arcingand/or a reduced deposition rate. With moving magnets, it becomesproblematic to cover areas of the target that are not getting erodedwith shields that could prevent back-scattered coating material orreactive gases from building up a layer of undesirable material on thetarget surface. Typically, with moving magnets, the bigger the ratio ofthe target area to the magnet area, the worse these problems can become.

There is a need in the sputtering art to reduce non-uniform erosion ofthe target and provide improved target utilization. There is a furtherneed to provide improved deposition rates and improved uniformity of thedeposited films when depositing onto large-area substrates.

SUMMARY

In accordance with one aspect, a magnetron sputtering system, e.g., areactive sputtering system, includes vacuum chamber and a substratemount for mounting a substrate within the vacuum chamber. A plurality ofcathode assemblies in the vacuum chamber includes a first set of one ormore cathode assemblies and at least one other set of one or morecathode assemblies, e.g., a second set of one or more cathodeassemblies. The plurality of cathode assemblies is configured forsputtering, e.g., reactive sputtering. Each cathode assembly includes atarget comprising sputterable material with an at least partiallyexposed planar sputtering surface. A target support is configured tosupport the target in the vacuum chamber and rotate the target relativeto the vacuum chamber about a target axis. The cathode assemblies eachfurther comprises a magnetic field source, including a magnet array. Theplurality of cathode assemblies is configured such that when the firstset of cathode assemblies is operating the second set of cathodeassemblies is not operating, and when the second set of cathodeassemblies is operating the first set of cathode assemblies is notoperating. A cathode assemblies controller assembly is operative toactuate the first set of cathode assemblies for sputtering thesputterable material of the first set of cathode assemblies withoutactuating the second set of cathode assemblies, and to actuate thesecond set of cathode assemblies for sputtering the sputterable materialof the second set of cathode assemblies without actuating the first setof cathode assemblies. It should be understood that in at least certainembodiments of the inventive technology disclosed here, all or at leastsome of the cathode assemblies can be switched from one of the sets ofcathode assemblies to a different set of the cathode assemblies by thecathode assemblies controller.

In accordance with further aspects, a magnetron sputtering system, e.g.,a reactive sputtering system, includes a vacuum chamber and a substratemount for mounting a substrate rotatably about a central axis within thevacuum chamber. A plurality of cathode assemblies is arranged in aconfocal orientation about the central axis, including a first set ofone or more cathode assemblies and a second set of one or more cathodeassemblies, and is configured for sputtering, e.g., reactive sputtering.Each cathode assembly includes a target comprising sputterable materialhaving an at least partially exposed planar sputtering surface, a targetsupport configured to support the target in the vacuum chamber androtate the target relative to the vacuum chamber about a target axis,and a magnetic field source including a magnet array. The plurality ofcathode assemblies is configured such that when the first set of cathodeassemblies is operational the second set of cathode assemblies is idle,and when the second set of cathode assemblies is operational the firstset of cathode assemblies is idle. In at least certain embodiments ofthis disclosure, all or at least some of the cathode assemblies can beswitched back and forth between the different sets of cathode assembliesby the cathode assemblies controller.

In accordance with other aspects, a magnetron sputtering system includesa vacuum chamber and a substrate rotatably mounted about a central axiswithin the vacuum chamber and configured to rotate at a suitable speed,for example, a speed of between approximately 30 rpm and approximately1500 rpm. A plurality of cathode assemblies is arranged in a confocalorientation about the central axis, and includes a first set of twocathode assemblies and a second set of two cathode assemblies, and isconfigured for sputtering, e.g., reactive sputtering. Each cathodeassembly includes a target comprising sputterable material having an atleast partially exposed sputtering surface. A target support isconfigured to support the target in the vacuum chamber and rotate thetarget relative to the vacuum chamber about a target axis, with eachtarget axis being oriented with respect to the central axis at an angleof greater than 0 degrees and less than 90 degrees. The cathodeassemblies each further comprises a magnetic field source including amagnet array. A cathode assemblies controller comprises a timer tocontrol operation of the first set of cathode assemblies and the secondset of cathode assemblies, such that when the first set of cathodeassemblies is operational (i.e., is sputtering target material todeposit onto the substrate) the second set of cathode assemblies isidle, and when the second set of cathode assemblies is operational thefirst set of cathode assemblies is idle.

In at least certain exemplary embodiments, the magnetic field sourcecomprises a magnet array. In certain exemplary embodiments, such magnetarray is behind the target, i.e., on the side of the target opposite theerosion or sputtering surface (those terms being used interchangeablyhere and in the appended claims), e.g., opposite the side that will facethe substrate to be coated during use of the cathode assembly in asputtering operation. The magnet array may, for example, be atwo-dimensional array in a plane generally parallel to the planarerosion surface or planar sputtering surface of the target. Optionally,the cathode assembly also has a magnet array support configured tosupport the magnet array, e.g., in a stationary position during movementof the target in a vacuum chamber during sputtering. In certainexemplary embodiments the target support of the cathode assemblycomprises a frame. Optionally, in embodiments having a magnet array andsuch frame, the magnet array may be supported within the frame behindthe target. Optionally, the target may be water cooled.

In certain exemplary embodiments the cathode assembly further comprisesa mounting surface for fixed-position mounting to a vacuum chamber toposition the cathode assembly at least partially within the vacuumchamber. The target support of the cathode assemblies disclosed heretypically are operative to move the target relative to the mountingsurface during sputtering. In certain exemplary embodiments the planarsputtering surface of the target is circular and the target support isoperative to rotate the target in a vacuum chamber during sputtering,that is, to spin the target on an axis not parallel to, e.g., generallyperpendicular to, the target's planar sputtering surface. In certainexemplary embodiments the target support is operative to orbit androtate the target in a vacuum chamber during sputtering, wherein theorbiting and rotating are in generally the same plane. It should beunderstood that use of the term “generally” and similar terms here andin the appended claims is intended to mean approximately or within theconstraints of sensible, commercial engineering objectives, costs andcapabilities. In other exemplary embodiments the target support isoperative to move the target back and forth in the plane of the planarsputtering surface in a vacuum chamber during sputtering. In someembodiments the target support is operative to provide compound movementof the target, e.g., a combination of lateral and spinning movement,etc. In certain exemplary embodiments the cathode assembly is operativeto dither the magnet assembly during sputtering.

In accordance with another aspect, a cathode assembly for a sputteringsystem includes a target support configured to support a target having aplanar erosion surface. The target may define a target axis that issubstantially perpendicular to the planar erosion surface of the target.The target support is configured to rotate the target around the targetaxis. The cathode assembly may further include a magnetic field source,wherein the target support is configured to move the target relative tothe magnetic field source.

In accordance with another aspect, a cathode assembly for a sputteringsystem includes a target support configured to support a target havingan erosion surface and a magnetic field source. The target support isconfigured to rotate the target around an axis that is not parallel tothe erosion surface of the target. The target support is furtherconfigured to move the target relative to the magnetic field source.

In accordance with another aspect, a cathode assembly for a sputteringsystem has a target support and a magnet array that includes a pluralityof magnets arranged in a substantially two-dimensional planar array anddefining a substantially two-dimensional magnet plane. The targetsupport is configured to move a substantially planar target in a planesubstantially parallel to the substantially two-dimensional magnetplane.

Additionally, another aspect of the present invention is directed tomagnetron sputtering systems comprising a vacuum chamber, a cathodeassembly in accordance with the disclosure above, mounted to the vacuumchamber, and a magnetic field source for the erosion surface. At leastcertain exemplary embodiments of the magnetron sputtering systemsdisclosed here include a vacuum chamber having a mount for a workpiece,i.e., a substrate to be coated, a cathode assembly comprising a targetof sputterable material having an at least partially exposed planarsputtering surface and a target support configured to support and movethe target in the vacuum chamber during sputtering, and a magnetic fieldsource. The target support is configured to move the target relative tothe chamber, and typically relative to the magnetic field produced bythe magnetic field source. The target support in certain exemplaryembodiments is configured to rotate the target around an axis that isnot parallel to the erosion surface of the target, e.g., perpendicularto that surface. The magnetic field source may include a plurality ofmagnets arranged in a substantially two-dimensional array.

In at least certain exemplary embodiments of the magnetron sputteringsystems disclosed here, an energy source or power source (e.g. RF, DC,pulsed DC, dual alternating cathode DC) is provided to maintain thesputtering plasma during sputtering, typically during operation of themagnetron sputtering system for deposition of material from a targetonto a substrate in a vacuum chamber. It will be understood by thoseskilled in the art, given the benefit of this disclosure, that themagnetron sputtering systems typically will be used in a vacuum chamber.It can be mounted entirely inside or through the wall of a vacuumchamber. Typically, feedthroughs can be used to deliver power, coolingwater, etc. to the magnetron sputtering systems or otherwise into thechamber. In certain exemplary embodiments cooling liquid is used forcooling the target. For example, cooling liquid lines can be used tocirculate water or other cooling liquid to cool the target. In certainexemplary embodiments cooling liquid is circulated to a thermallyconductive backing plate for the target, e.g., a metal plate in thermalcontact with the target. Couplings along such cooling line(s) must beliquid-tight and accommodate the sliding and/or spinning movement of thetarget. In certain exemplary embodiments of the magnetron sputteringsystems disclosed here, a power source is provided to actuate the drivemechanism to move the substantially planar sputtering surface of thetarget during sputtering.

Another aspect of the present invention is directed to a method forsputtering. In accordance with this aspect, magnetron sputtering methodsare provided for deposition of target material on a substrate. Themagnetron sputtering methods according to this aspect comprise providinga vacuum chamber with a workpiece mount for mounting a substrate withinthe chamber during sputtering. A cathode assembly according to thedisclosure above is mounted to the vacuum chamber. A workpiece orsubstrate is mounted in the chamber via the workpiece mount. To sputtertarget material to deposit onto the substrate, the vacuum chamber isplaced under vacuum, for example, at a pressure of approximately 10⁻⁶Torr. Then, a sputtering gas, e.g. a working gas, typically a noble gassuch as argon, and in some cases a reactive gas, such as oxygen ornitrogen is fed into the vacuum chamber. Power is supplied to thecathode assembly to initiate and maintain a sputtering plasma and tomove the substantially planar sputtering surface of the target duringsputtering. In certain exemplary embodiments the cathode assemblycomprises a drive mechanism to rotate the sputtering surface, typicallyin the plane of the sputtering surface, e.g., about an axis that isperpendicular to the substantially planar surface of the target. Incertain exemplary embodiments the drive mechanism moves thesubstantially planar sputtering surface of the target relative to themagnet array, which may be stationary, i.e., stationary relative to thechamber, the sputtering plume, the substrate (ignoring any spinningmotion of the substrate), the workpiece mount and the like. Optionally,in addition to motion of the target's sputtering surface, the magneticfield may be in motion during sputtering, e.g., by oscillating a magnetarray proving all or some of the magnetic field. The sputtering may incertain exemplary embodiments be long-throw sputtering of targetmaterial onto the substrate.

The sputtering methods disclosed here in accordance with certainexemplary embodiments include providing a cathode assembly having amagnet array and a movable target support connectable to a drivemechanism. The magnet array optionally includes a plurality of magnetsarranged in a substantially planar two-dimensional array. Such methodsfurther include providing a substrate, providing a sputtering gas, andsupplying power to the cathode assembly. The movable target support isdriven to move the substantially planar surface of the target relativeto the substantially planar two-dimensional array of the plurality ofmagnets.

Those of ordinary skill in the art will recognize that the cathodeassemblies and sputtering systems and methods disclosed here presentsignificant technical and commercial advantages. Likewise, those ofordinary skill in the art will recognize that innumerable modificationscan be made and other features are aspect added without departing fromthe principles disclosed here.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing Summary, as well as the following Detailed Description,will be better understood when read in conjunction with the accompanyingdrawings.

FIG. 1 is a schematic illustration of a sputtering system in accordancewith certain exemplary embodiments of the present disclosure;

FIG. 2 is a cross-sectional side view of a cathode assembly inaccordance with an exemplary embodiment of the present disclosure;

FIG. 3 is an external perspective view of a cathode assembly inaccordance with the exemplary embodiment of FIG. 2;

FIG. 4 is a schematic illustration of a sputtering system in accordancewith other exemplary embodiments of the present disclosure;

FIG. 5 is a schematic illustration of a sputtering system in accordancewith even other exemplary embodiments of the present disclosure; and

FIG. 6 is schematic illustration of an alternative embodiment of atarget and magnetic array unit of the sputtering system of FIG. 1;

FIG. 6A is a plan view of a round or circular magnet array (that is,comprising magnets laid out in a round or circular pattern in a planeparallel to the planar sputtering surface of the target) suitable for atleast certain exemplary embodiments of the cathode assemblies andsputtering systems disclosed here.

FIG. 6B is a sectional elevation taken through line A-A of FIG. 6A.

FIG. 7A is a plan view of a non-round, specifically an apple-shaped orcardioid magnet array (that is, comprising magnets laid out in acardioid pattern in a plane parallel to the planar sputtering surface ofthe target) suitable for at least certain exemplary embodiments of thecathode assemblies and sputtering systems disclosed here.

FIG. 7B is a sectional elevation taken through line A-A of FIG. 7A.

FIG. 8 is a schematic illustration of an alternative embodiment of asputtering system with two cathode assemblies.

FIG. 9 is a schematic illustration of an alternative embodiment of asputtering system with a plurality of assemblies having targets orientedat an angle with respect to central axis of a substrate.

FIG. 10 is a schematic illustration of an alternative embodiment of asputtering system with three cathode assemblies.

FIG. 11 is a schematic illustration of an alternative embodiment of asputtering system with four cathode assemblies.

The figures referred to above are not drawn necessarily to scale, shouldbe understood to provide a representation of particular aspects of theinvention, and may be merely conceptual in nature and illustrative ofthe principles involved. Some features of the cathode assembly andsputtering system depicted in the drawings have been enlarged ordistorted relative to others to facilitate explanation andunderstanding. The same reference numbers are used in the drawings forsimilar or identical components and features shown in variousalternative aspects. Cathode assemblies and sputtering systems asdisclosed herein would have configurations and components determined, inpart, by the intended application and environment in which they areused.

DETAILED DESCRIPTION OF CERTAIN EXEMPLARY EMBODIMENTS

The basic sputtering processes are well understood for depositing targetmaterials on substrates. The teachings presented herein with respect tocathode assemblies, magnetron sputtering systems and methods may beapplied to any sputtering process and apparatus that uses magneticfields to enhance the sputter deposition process. Further it should beunderstood the present disclosure contemplates that all discloseddetails, including optional and alternative features and details and thelike, may be used all together, in any subset, and in any operativecombination or permutation.

Reference here to the disclosed cathode assemblies of the magnetronsputtering systems being mounted to or on or in a vacuum chamber shouldbe understood to mean mounting on (i.e., wholly or partially on) thechamber, in (i.e., wholly or partially in) the chamber, to the chamber,within (i.e., wholly or partially within) the chamber, and/or the like.Thus, with the cathode assembly mounted to a vacuum chamber, certaincomponents or portions of components or parts of the cathode assemblymay be wholly or partly inside the chamber, some may extend through thewall of the chamber, some may be wholly or partly outside the chamber,etc. As disclosed above, the disclosed cathode assemblies in at leastcertain exemplary embodiments have a mounting surface for fixed-positionmounting to a vacuum chamber. As used here, the term “fixed-positionmounting to a vacuum chamber” means that, when a cathode assemblyaccording to such embodiments are mounted to a chamber, the mountingsurface of the cathode assembly is fixed or immovable relative to themain body of the chamber, e.g., relative to a chamber wall to which itis bolted or otherwise secured. As a non-limiting example, if thecathode assembly is mounted at a hole or port in the outer wall of avacuum chamber, the mounting surface may be in fixed, surface-to-surfacecontact with the inner and/or outer surface of the chamber wall. Certainexemplary embodiments of the cathode assemblies disclosed here will havemore than one mounting surface and optionally more than one mountingsurface with fixed-position mounting to a vacuum chamber.

In typical operations employing a magnetron sputtering system comprisinga cathode assembly in accordance with the present disclosure mounted toa vacuum chamber, the cathode assembly is at least partially within thevacuum chamber. The target in a typical sputtering operation will bewithin the vacuum chamber or in communication with the main portion ofthe chamber holding the substrate and, as disclosed above, will besupported for rotation or other movement during sputtering. In thoseembodiments having a mounting surface as discussed immediately above,the target support is operative to move the target relative to suchmounting surface. In that regard, it should be understood that referencehere to the target being moveably supported by the target support, andsimilar descriptions, such as that the target support is operative tomove the target, mean that the target support is operative to move thetarget during sputtering, i.e., during use of the magnetron sputteringsystem in a sputtering operation, typically in a vacuum chamber. Thatis, the target support is operative to move the target relative to theplasma plume that will be created by operation of the magnetronsputtering system during sputtering, or relative to the wall(s) of thechamber, or relative to the main body of the chamber or to the mainstructure or superstructure of the cathode assembly, or to all of them.In typical embodiments, the superstructure of the cathode assembly ismounted to a chamber wall in fixed position to the chamber, and thetarget support is operative to move the target relative to the plasmaplume, chamber and superstructure of the cathode assembly.

The term “approximately” as used herein is meant to mean close to, orabout, a particular value, within the constraints of sensible commercialengineering objectives, costs, manufacturing tolerances, andcapabilities in the field of sputtering systems and cathode assemblymanufacturing and use. Similarly, the term “substantially” as usedherein is meant to mean mostly, or almost the same as, within theconstraints of sensible commercial engineering objectives, costs,manufacturing tolerances, and capabilities in the field of sputteringsystems and cathode assembly manufacturing and use.

Referring now to the drawings, FIG. 1 is a schematic view of sputteringsystem 100 according to one non-limiting embodiment of the invention.Sputtering system 100 includes a vacuum chamber 110 having a sputteringgas inlet 112, a work piece holder 120 and a cathode assembly 200.Cathode assembly 200 and work piece holder 120 are located within vacuumchamber 110. A substrate (S) is mounted to work piece holder 120.Typically, a sputtering system also includes a vacuum pump, a powersource, and one or more sputtering gas sources (not shown).

FIG. 2 is a cross-section side view of cathode assembly 200 according tocertain aspects of the invention. Cathode assembly 200 includes amagnetic field source, such as magnetic array unit 210, and a targetsupport 220. Referring also to FIG. 3, cathode assembly 200 typicallyincludes a housing 202, a means for cooling the cathode assembly 204 anda dark space shield 206.

As presented in FIGS. 1 and 2, target support 220 holds target 222within a frame 224. Target 222, which may be formed of one or moretarget materials, is a substantially planar target having a planar topsurface 223. Top surface 223 is an erosion surface that supplies thematerial to be deposited on substrate (S). The target material that issputtered may comprise any suitable material as would be apparent tothose of ordinary skill in the art. Target 222 may be bonded orotherwise attached to a target backing plate. Reference here to thesputtering or erosion surface of the target being planar or the likemeans that it is generally flat or lying in a plane. In that regard, itwill be understood by those of ordinary skill in the art given thebenefit of this disclosure, that the sputtering surface will, of course,not be removed perfectly evenly during sputtering and, so will developan erosion pattern during sputtering. The sputtering surface should beunderstood to be planar, as that term is used here (alternativelyreferred to here and in the claims, either before or after such erosionpattern develops, as being generally planar), notwithstanding sucherosion pattern. Target support 220 further includes a hollow shaft 226extending between frame 224 and drive mechanism 230.

Magnetic array unit 210 can be any suitable source of magnetic fieldlines as would be apparent to a person of ordinary skill in the art,given the benefit of the present disclosure. According to certainexemplary embodiments of the present invention, magnetic array unit 210includes one or more permanent magnets 211 arranged in a substantiallytwo-dimensional array. A substantially two-dimensional array of magnetsincludes a plurality of magnets extending in a first direction and aplurality of magnets extending in a second direction. The array issubstantially two-dimensional even if some of the magnets do not lieprecisely in the plane. Further, the first and second directions may belinear or curvilinear. When the first and second directions are bothlinear, the two-dimensional array is planar. When at least one of thefirst and second directions is curvilinear, the two-dimensional array isno longer planar, but curves out of the plane. As shown in theembodiment of FIG. 2, the substantially two-dimensional array is planar,i.e. the magnets lie substantially in a flat plane. Further, thesubstantially two-dimensional planar array lies parallel to top surface223 of target 222. A central shaft 212 supports magnetic array unit 210.Magnetic array designs are known within the industry, and typically usehigh strength magnets, which are commercially available and commonlyknown.

According to certain exemplary embodiments of the invention, as shown inFIGS. 1 and 2, magnetic array unit 210 is stationary relative to vacuumchamber 110 during deposition and target support 220 is movable relativeto vacuum chamber 110 during deposition. A drive mechanism 230 isdrivably connected to target support 220. In operation of suchembodiments, drive mechanism 230 causes shaft 226, frame 224 and target222 to rotate around a target axis 225 (see arrow A in FIG. 1). Targetaxis 225 is substantially perpendicular to the plane of planar topsurface 223. In certain embodiments, target 222 may be water cooled.

According to certain exemplary embodiments of the invention, as shown inFIG. 4, magnet array 210 moves relative to target axis 225 of target222. As a non-limiting example, magnet array 210 may oscillate radially(back and forth in the direction of arrow B) from target axis 225, inthe plane of the magnetic array, using relative small displacements.This may serve to further smooth out any erosion pattern formed onerosion surface 223. As another example, magnet array 210 may move inthe plane of the magnet array in an X- or Y-direction (or both an X- andY-direction) relative to target axis 225.

In another embodiment, as shown in FIG. 6, target 222 isconically-shaped. Magnetic field source 210 is located within the coneof target 222. In an exemplary embodiment, magnetic field source has atwo-dimensional, curvilinear, array of magnets, i.e., the array ofmagnets essentially follows the curve of the cone. Conically-shapedtarget 222 may rotate around an axis 227 that extends through the centerof the cone (see arrow A). Magnetic field source 210 may be stationaryor may oscillate slightly parallel to the surface 223 of the cone (seearrow B).

Referring now to FIGS. 6A and 6B, a round or circular magnet array isshown that is suitable for at least certain exemplary embodiments of thecathode assemblies and sputtering systems disclosed here. The magnetarray 240 has magnets 242 laid out in a round or circular pattern in aplane, specifically, a plane 243 parallel to the planar sputteringsurface of the target. The magnets include outer ring 242A and innerring 242B. The magnets of both the inner and outer rings are centeredabout point “C” on a support plate 241.

Referring now to FIGS. 7A and 7B, a non-circular magnet array 244 isshown, specifically, an apple-shaped or cardioid shaped array that issuitable for at least certain exemplary embodiments of the cathodeassemblies and sputtering systems disclosed here. The magnet array 244has magnets 246 laid out in such cardioid pattern in a plane 247parallel to the planar sputtering surface of the target. The magnetsinclude outer (non-circular) ring 246A and inner (non-circular) ring246B. The magnets are positioned on a support plate 248.

In yet other exemplary embodiments, as best shown in FIG. 5, targetsupport 220 may move linearly, parallel to the plane of surface 223 (seearrow C). This may be particularly useful if the planar target issubstantially rectangular or elongate. In such instance, the widthdimension of target 222 may be substantially the same as the widthdimension of magnetic array unit 210, while the length dimension oftarget 222 may be considerably longer than the length dimension ofmagnetic array unit 210. Thus, the rectangular or elongate target 222,may be slidably driven back-and-forth in its length direction overmagnetic array unit 210 in order to develop a substantially uniformerosion profile while maintaining a stationary deposition plume. Inother exemplary embodiments, target support 220 may move by acombination of movements within the plane. For example, target support220 may move linearly in a first direction and also rotate round an axisperpendicular to the plane of top surface 223. Alternatively, targetsupport 220 may move linearly in the plane of top surface 223 in twomutually orthogonal directions.

The sputtering processes disclosed here, according to an aspect of theinvention, includes placing a cathode assembly 200 having a magnet array210 and a target support 220 in a vacuum chamber 110. The target support220 is connected to drive mechanism 230. The magnet array 210 includes aplurality of magnets arranged in a substantially planar two-dimensionalarray. Target support 220 includes a target 222 having a substantiallyplanar erosion surface 223. A substrate, upon which material from thetarget is to be deposited, is placed in the vacuum chamber. A vacuum isdrawn in the vacuum chamber and an inert sputtering gas, optionally areactive sputtering gas, or a combination of inert and reactivesputtering gases are introduced into the chamber. An electricalpotential is applied to the cathode assembly to initiate a plasma. Poweris supplied to cathode assembly to drive the drive mechanism and therebymove target support 220 relative to the substantially planartwo-dimensional array of the plurality of magnets of the magnet fieldsource 210. Each of the cathode assemblies of the system may optionallybe of substantially the same configuration as disclosed here, althoughvarious alternative cathode assembly configurations known to thoseskilled in the art may be used in addition or instead.

During sputtering, the ion density of the plasma formed will be higherin the area near magnetic array unit 210 as compared to the plasma inthe area of the target remote from magnetic array unit 210. With anincreased ion density, material is sputtered from the target at a higherrate. For certain applications requiring improved uniformity, thecathode assembly may be spaced a greater distance from the substrate(S), forming a “long-throw” deposition plume. The substrate may be spunabout its axis to further improve uniformity. As an example of along-throw sputtering process, cathode assembly 200 may be spaced fromthe substrate (S) by about 150 mm to about 500 mm in both dimensions ofoffset and displacement.

According to the exemplary embodiments disclosed herein, the area of thetarget's erosion surface can be made almost arbitrarily large. Thisreduces the amount of etch or erosion from each deposition cycle for anygiven area of the target surface. Further, large targets provide anincreased inventory of target material. It is expected that the ratio ofthe area of the planar erosion surface of the target to the area of thefootprint of the magnetic field source would typically be greater thanapproximately 3.0, and that the ratio could easily be greater thanapproximately 4.0 or 5.0.

Due to the improved erosion profile, it is expected that the utilizationof the target could exceed 50% or even 60%. In certain instances, it isexpected that utilization of the target in a commercially efficientsputtering operation could range from approximately 60% to approximately85%.

In the embodiment of a sputtering system 100 schematically shown in FIG.1, a single cathode assembly is shown. It is to be understood that asputtering system 100′ including a plurality of cathode assemblies maybe positioned within vacuum chamber 110, as seen in FIGS. 8-10. Furtherit should be understood that the cathode assembly disclosed herein mayhave utility in other sputtering system configurations, including thosesputtering systems configured to process large area substrates.

In certain embodiments, cathode assembly 200 may be powered by a DCpower supply, such as a Pinnacle Plus power supply available fromAdvanced Energy of Denver, Colo.

As illustrated in FIGS. 8-10, a plurality of cathode assemblies 200 arepositioned within vacuum chamber 110. In the embodiment illustrated inFIG. 8, two cathode assemblies 200A, 200B are positioned within vacuumchamber 110 along with a single substrate S rotatably mounted onworkpiece holder 120. In certain embodiments, substrate S may beconfigured to rotate around a central axis 232, as shown by arrow D. Incertain embodiments, central axis 232 may be substantially perpendicularto a planar surface of substrate S, and may be substantially parallel totarget axes 225, about which targets 222A, 222B of cathode assemblies200A, 200B, respectively, rotate.

It is to be appreciated that in embodiments where sputtering system 100′includes multiple cathode assemblies 200 that they may be powered by anAC power supply, such as a PEII Series power supply available fromAdvanced Energy of Denver, Colo. An AC power supply does not require ananode, thereby eliminating the problem of coating build-up on the anode.

In certain embodiments, substrate S may be configured to rotate at aspeed of between approximately 30 rpm and approximately 1500 rpm, andmore typically between approximately 100 rpm and approximately 1000 rpm.

In certain embodiments it may be desirable to deposit alternating layersof different materials and/or different thicknesses on substrate S. Inorder to vary the type and/or thickness of the material layer depositedon substrate S, the cathode assemblies 200A, 200B may be configured suchthat one or more of the cathode assemblies 200A, 200B are operational atthe same time that one or more other of the cathode assemblies 200A,200B are idle. Thus, sets or subsets of the plurality of cathodeassemblies 200A, 200B may be operated at different times.

It is also to be appreciated that the thickness of the layer of materialdeposited on substrate S may be controlled by varying the time that acathode assembly 200 is operational, with longer operational timesproducing thicker layers of material. In certain embodiments, one ormore cathode assemblies 200 may be operated to provide a calibrationcoating run in order to accurately measure the deposition rate onsubstrate S. A calibration coating run may be a single layer of materialin certain embodiments. In other embodiments, the entire test coatingdesign, i.e., multiple layers, being produced may be incorporated in thecalibration coating run. It is to be appreciated that commercialthickness monitors, e.g., oscillating quartz crystal thickness monitors,may be used to measure the thickness of substrate S.

In certain embodiments, the thickness of the film layer deposited onsubstrate S can be, for example, between approximately 10 andapproximately 200 nm and more typically between approximately 5 nm andapproximately 10 microns. As noted above, different materials may bedeposited by different cathode assemblies 200 simultaneously positionedwithin vacuum chamber 110. In certain embodiments, for example, one ormore cathode assemblies 200 each may include a target 222 of, e.g.,tantalum for sputtering to form tantalum layers on substrate S mountedin vacuum chamber 110, while one or more other cathode assemblies 200each may include a target of, e.g., silicon (“Si”), which are sputteredin the presence of oxygen in the vacuum chamber, while the tantalumcathode assemblies are not being actuated, to form silicon oxide layersalternating with the tantalum layers on the surface of substrate S.

It is to be appreciated that any number of layers of different materialsfrom various targets 222 may be deposited on substrate S. The materialsof the targets 222 may also be combined with different reactive gasses.Thus, for example, target 222A could be used to deposit a first layerformed of Si on substrate S, after which oxygen may be added to vacuumchamber 110 and combined with target 222A to deposit a second layerformed of SiO₂ on substrate S, after which target 222B could be used todeposit a third layer of tantalum on substrate S. It is to beappreciated that after the second layer of SiO₂ is deposited onsubstrate S that vacuum chamber 110 would be pumped out to remove someor all of the oxygen that had been introduced.

It should be understood that various alternative embodiments inaccordance with this disclosure may have more than two sets of cathodeassemblies, each set having a different kind of target material. Eachsuch set of cathode assemblies may comprise one or more cathodeassemblies. Thus, magnetron sputtering systems as disclosed hereoptionally may have three, four of more sets of cathode assembliesmounted and operational for sputtering within the same vacuum chamber,wherein each set comprises one or more cathode assemblies having atarget material different from the target material of the other sets ofcathode assemblies.

In accordance with various alternative embodiments, some or all of thedifferent cathode assemblies 200 may be controlled by a cathodeassemblies controller assembly 234 operative to selectively actuate thedifferent sets of cathode assemblies sequentially with one another. Incertain embodiments cathode assemblies controller assembly 234 isoperative to selectively actuate different sets of cathode assemblieswholly or partly simultaneously, e.g., with complete or partial overlapof their actuation time periods. The cathode assemblies controllerassembly 234 optionally may be further operative to switch all or atleast some of the cathode assemblies back and forth between differentsets of cathode assemblies, i.e., from one set to another. Together withinstalling a different target material in a cathode assembly switched toa different set, this function of the controller can provideadvantageous flexibility in achieving desired deposition rates fordifferent materials to be sputtered and deposited onto the substrate.

Cathode assemblies controller assembly 234 may include any combinationof hardware and/or software elements suitable to independently controlthe operation of each of the cathode assemblies 200. For example,cathode assemblies controller assembly 234 may comprise a mechanicalrelay with software configured to send a message to turn the relay onand off. It is to be appreciated that in certain embodiments, cathodeassemblies controller assembly 234 may be operative to control theactuation of cathode assemblies 200 in response to a changing opticalproperty of substrate S as a layer of substrate S is being deposited. Inthe illustrated embodiment, a single cathode assemblies controllerassembly 234 is operably connected to both of cathode assemblies 200A,200B to control their operation. It is to be appreciated that in otherembodiments, a separate cathode assemblies controller assembly 234 couldbe provided on each cathode assembly 200 positioned within vacuumchamber 110. In order to vary the times at which cathode assemblies200A, 200B operate, cathode assemblies controller assembly 234 maycomprise a timer configured to control the operation of cathodeassemblies 200A, 200B, actuation of which may be controlled in a simpleon/off sequencing arrangement. The timer may be configured toalternately actuate cathode assemblies 200A, 200B on and off for asingle specified time interval, for example, 30 seconds on and then 30seconds off.

In certain embodiments, cathode assemblies controller assembly 234 maybe configured to control operation of cathode assemblies 200 using acombination of time intervals and control based on an optical propertyof substrate S. For example, cathode assemblies controller 234 may beconfigured to use both a timer and a thickness monitor, e.g., a quartzcrystal thickness monitor. In such an embodiment, actuation of cathodeassemblies 200 may be controlled based on time intervals for a period oftime, followed by control based on the thickness monitor. The thicknessmonitor may be configured to determine a thickness of a layer ofmaterial being deposited on substrate S, and cathode assembliescontroller assembly 234 may be configured to actuate a specific cathodeassembly 200, or specific combination of cathode assemblies 200, andkeep that specific cathode assembly 200 or combination of cathodeassemblies 200 operating until a specified thickness of material isdeposited on substrate S.

In certain embodiments, cathode assemblies controller assemblies 234 maybe configured to operate cathode assembly 200A and cathode assembly 200Bsimultaneously. In other embodiments, cathode assemblies controllerassemblies 234 may be configured to operate cathode assembly 200A andcathode assembly 200B in alternating fashion. It is to be appreciatedthat when cathode assembly 200A and cathode assembly 200B operate inalternating fashion, they may each be operational for the same length oftime, or different lengths of time.

In certain embodiments, as illustrated in FIG. 9, cathode assemblies200A, 200B may be oriented at an angle with respect to central axis 232.As illustrated here, cathode assemblies 200A, 200B may be in a confocalorientation with each target axis 225 of cathode assembly 200A, 200Boriented at angle E with respect to central axis 232. In certainembodiments, angle E may be between approximately 20° and approximately40°, and more particularly approximately 30°.

Another embodiment of sputtering system 100′ with a plurality of cathodeassemblies 200 is illustrated in FIG. 10. In this embodiment, threecathode assemblies 200A, 200B, 200C, with respective targets 222A, 222B,222C may be positioned in vacuum chamber 110. In certain embodiments,cathode assemblies 200A, 200B, 200C may be oriented in a confocalarrangement as described above with respect to FIG. 8.

In such an embodiment with three cathode assemblies 200A, 200B, 200C,cathode assemblies controller assembly 234 may be configured to operatethe cathode assemblies in different modes. For example, in certainembodiments, all three cathode assemblies 200A, 200B, 200C may beconfigured to operate at the same time and, therefore, they would all beturned on and turned off at the same time. In other embodiments, a firstset of the three cathode assemblies 200A, 200B, 200C may be operationalwhile a second set is non-operational. For example, the first set mayinclude cathode assembly 200A, and the second set may include cathodeassemblies 200B, 200C.

In such an embodiment cathode assembly 200A of the first set may beoperational for a first period of time T1 while cathode assemblies 200B,200C of the second set are idle. Cathode assemblies 200B, 200C of thesecond set may then be operational for a second period of time T2 whilecathode assembly 200A of the first set is idle. The first set and secondset may then be operated in an on/off fashion alternately for a desiredlength of time, or until a desired thickness of material is deposited onsubstrate S.

It is to be appreciated that in certain embodiments first period of timeT1 may be equal to second period of time T2, while in other embodimentsfirst period of time T1 may be shorter or longer than second period oftime T2.

It is to be appreciated that the first set and the second set can beconfigured differently as sputtering system 100′ is operated. Forexample, in certain embodiments, the first set could include cathodeassembly 200B, and the second set could include cathode assemblies 200A,200C. In other embodiments, the first set could include cathode assembly200C, and the second set could include cathode assemblies 200A, 200B.

In further embodiments, sputtering system 100′ could include three sets,with the first and second sets operating in alternating fashion, and thethird set being non-operational, e.g., disabled or simply left idleduring the deposition run. In such an embodiment, the three sets couldhave a fixed configuration during the entire time that material isdeposited on substrate S. Thus, for example, the first set could includecathode assembly 200A, the second set could include cathode assembly200B, and the third set could include cathode assembly 200C. In such anembodiment, cathode assembly 200A and 200B would alternate operation,with cathode assembly 200C being non-operational for the entire timethat material is deposited on substrate S.

In embodiments with a plurality of cathode assemblies 200, it is to beappreciated that the cathode assemblies 200 that are grouped indifferent sets and are operational in alternating fashion could changeduring the time that material is deposited on substrate S. For example,initially cathode assemblies 200A and 200B could operate in alternatingfashion for a selected period of time, while cathode assembly 200C isnon-operational. Then, cathode assemblies 200A and 200C could operate inalternating fashion for another selected period of time, while cathodeassembly 200B is non-operational. This could be followed by cathodeassemblies 200B and 200C operating in alternating fashion for anotherselected period of time, while cathode assembly 200A is non-operational.It is to be appreciated that any combination of the three cathodeassemblies 200A, 200B, 200C could be used in alternating operational andnon-operational fashion to deposit material on the surface of substrateS.

Another embodiment of a sputtering system 100′ with a plurality ofcathode assemblies 200 is illustrated in FIG. 11. In this embodiment,four cathode assemblies 200A, 200B, 200C, 200D, with respective targets222A, 222B, 222C, 222D may be positioned in vacuum chamber 110. Incertain embodiments, cathode assemblies 200A, 200B, 200C, 200D may beoriented in a confocal arrangement as described above with respect toFIG. 8.

In such an embodiment with four cathode assemblies 200A, 200B, 200C,200D, cathode assemblies controller assemblies 234 may be configured tooperate the cathode assemblies in different modes. For example, incertain embodiments, all four cathode assemblies 200A, 200B, 200C, 200Dmay be configured to operate at the same time and, therefore, they allwould be turned on and turned off at the same time. In otherembodiments, two or more sets of cathode assemblies 200A, 200B, 200C,200D could be operational and/or non-operational at different times.

For example, two sets of cathode assemblies could be provided with thefirst set including cathode assemblies 200A, 200 B, and the second setincluding cathode assemblies 200C, 200D. In such an embodiment, thefirst set may be operational for a first period of time T1 while thesecond set is idle. Then, the second set may be operational for a secondperiod of time T2 while the first set is idle. The first set and secondset may then be operated in an on/off fashion alternately for a desiredlength of time, or until a desired thickness of material is deposited onsubstrate S.

It is to be appreciated that in certain embodiments first period of timeT1 may be equal to second period of time T2, while in other embodimentsfirst period of time T1 may be shorter or longer than second period oftime T2.

It is to be appreciated that the first set and the second set can beconfigured differently as sputtering system 100′ is operated. Forexample, in certain embodiments, the first set could include cathodeassemblies 200A, 200C, and the second set could include cathodeassemblies 200B, 200D. In other embodiments, the first set could includecathode assemblies 200A, 200D, and the second set could include cathodeassemblies 200B, 200C.

In other embodiments, a first set could include two cathode assemblies,a second set could include a single cathode assembly, and a third setcould include a single cathode assembly. Thus, for example, the firstset could include cathode assemblies 200A, 200B, while the second setcould include cathode assembly 200 C, and the third set could includecathode assembly 200D. In such an embodiment, the first set could beoperational for a first period of time T1, while the second and thirdsets are non-operational. The second set could then be operated whilethe first and third sets are non-operational. Finally, the third setcould then be operated while the first and second sets arenon-operational.

It is to be appreciated that the plurality of cathode assemblies 200 insputtering system 100′ could include any number of cathode assemblies,and that the number of cathode assemblies can be greater than four.Additionally, it is to be appreciated that each set of cathodeassemblies can include one or more cathode assemblies. Further, asdiscussed above, the configuration of the sets of the plurality ofcathode assemblies could be changed during the process of depositing alayer of material on substrate S.

In certain embodiments, as illustrated in FIG. 12, a first pin mask 700may be positioned within vacuum chamber 110, and may be used duringdeposition to reduce film deposition thickness over a portion of thesurface of substrate S. Importantly, the amount or degree of filmthickness reduction varies in the radial direction of the substratesurface, i.e., in the direction from the center 702 of substrate S(i.e., the point coincident with its axis of rotation) toward itscircumferential edge 704. Deposition using multiple rotary magnetroncathodes 200 as disclosed herein together with one or more pin masks 700can achieve improved deposition thickness accuracy and uniformity. Useof first pin mask 700 during a deposition run can partially or entirelycorrect unwanted deposition thickness errors, especially unwanted filmthickness variation in the radial direction of the coated surface ofsubstrate S.

Deposition using multiple rotary magnetron cathodes 200 as disclosedhere together with one or more pin masks 700 can achieve improveddeposition thickness accuracy and uniformity. Consequently, opticalfilters can be produced meeting exacting performance specifications, andhigher yields of in-spec optical filters can be achieved from a coatedsubstrate S produced by a deposition run.

First pin mask 700 (referred to as such because in certain preferredembodiments it is generally pin or dagger shaped) may be elongate andgenerally planar. It is to be appreciated that first pin mask 700 mayhave a shape other than a pin or dagger shape. Typically, first pin mask700 has a base 706 that may be rotationally or pivotally mounted tovacuum chamber 110 at a point radially spaced from circumferential edge704 of substrate S. An arm 707 may connect first pin mask 700 to base706. First pin mask 700 may lie in a plane parallel to the close planeof the substrate surface being coated, and typically may be spaced fromthe plane of substrate S, e.g., by about 0.2 to about 1.0 cm. First pinmask 700 may sit generally between the target 222 (not visible here) andsubstrate S. In the embodiment illustrated in FIG. 12, first pin mask700 can be seen to extend longitudinally from base 706 towardcenterpoint 702 of substrate S. Alternatively, in some embodiments thepin mask may be pivoted to a different orientation while still masking aportion of substrate S.

As mentioned above, the amount or degree of film thickness reductioncaused by first pin mask 700 varies in radial direction R along thesurface of substrate S. This is achieved by varying the lateral width Wof first pin mask 700 along its longitudinal axis. That is, the lateralwidth W of first pin mask 700 differs along its axial length, generallywidening and/or narrowing once or more times smoothly or continuously.

In the illustrated embodiment, lateral width W of first pin mask 700 hasa first value at its distal end 708, which is positioned proximatecenterpoint 702 of substrate S, and then widens to a second value at acentral point 710, and from there it narrows to a third value atproximal end 712, where first pin mask 700 is connected to arm 707, withthe third value being larger than the first, or minimum, value butsmaller than the second, or maximum, value. The first value at distalend 708 is a point, the second value may be approximately 4% of thecircumference of substrate S at that point, and the third value may beapproximately 0.5% of the circumference of substrate S at that point. Insuch an embodiment, first pin mask 700 may have a substantiallypear-shaped outline.

As can be seen in FIG. 12, central point 710 corresponds to, i.e.,overlies (or underlies), a circumferential portion 714 of the surface ofsubstrate S, being in a central portion of first pin mask 700 betweencenterpoint 702 of substrate S and the circumferential edge 704 ofsubstrate S. Likewise, proximal end 712 of first pin mask 700corresponds to, i.e., overlies (or underlies), circumferential portion716 of the surface of substrate S, which is proximate circumferentialedge 704 of substrate S. Since lateral width W of first pin mask 700 atcircumferential portion 714 is greater than lateral width W of first pinmask 700 at circumferential portion 716, deposition thickness will bereduced a greater amount by the pin mask at circumferential portion 714than at circumferential portion 716 of the surface of substrate S.

It is to be appreciated that lateral width W of first pin mask 700 ateach point along its axial length overlapping the surface of substrate Sbeing coated corresponds to the desired amount of film thicknessreduction at that corresponding radial location of the surface ofsubstrate S. The configuration of first pin mask 700 suitable for aparticular deposition run or for deposition of a particular layer or setof layers (e.g., for some or all of a set of layers that alternate withother layers of a different material) on substrate S corresponds to thefilm thickness error correction desired. The lateral width W at eachaxial location along the length of first pin mask 700 generally isproportional to the thickness error at the corresponding radial locationof the surface of substrate S.

The deposition thickness error to be corrected at each radial locationalong substrate S, and correspondingly a suitable configuration for apin mask in accordance with this disclosure, including the lateral widthat each point along the axial length of the pin mask, can be determinedby any suitable means, including, e.g., by estimation or predictivecalculation, or empirically based on measured radial depositionthickness variation on a substrate in a preliminary or test depositionrun done without the benefit of a pin mask.

In certain exemplary embodiments, the layer thickness error isdetermined empirically by conducting a test run of all or a portion of aplanned deposition run without first pin mask 700, and then measuringthe optical thickness and/or other property or properties of theresulting coating at multiple radial locations along substrate S. Themeasured values determine the shape or profile of first pin mask 700needed to correct the error. Optionally, the value of the measuredproperty for each of several different radial distances from thecenterpoint of the substrate can be taken as the average of the valuesmeasured at multiple locations spaced circumferentially at the sameradial distance from centerpoint 702.

Average values can then be similarly determined for each of multipleadditional radial distances from centerpoint 702 of substrate S. Thedifference between the desired property value and the measured propertyvalue corresponds to the thickness error. As noted above, the requiredlateral width W of first pin mask 700 at each point along itslongitudinal axis is generally proportional to the thickness error atthe corresponding radial location along substrate S. The wider first pinmask 700 is at a given axial location, the greater the reduction indeposition thickness at the corresponding radial location alongsubstrate S. More specifically, the wider the pin mask at a particularaxial location (corresponding to a radial location on the spinningsubstrate), the greater the reduction in deposition rate at thatlocation. The total reduction in deposition thickness is determined byboth the width of the pin mask and the time duration it is deployedduring the deposition of the layer in question. The pin mask can bedeployed for all or only a portion of the time during which a layer isbeing deposited, with correspondingly greater or less reduction indeposition thickness of the layer. Thus, the pin mask lateral width at aparticular axial location taken together with the portion of a layer'sdeposition time during which the mask is deployed to shadow thesubstrate together render the desired reduction in layer thickness atthe corresponding axial location on the substrate.

Thus, collectively, the deposition variation or error values determinedfor multiple radial locations along substrate S determine the shape orprofile of first pin mask 700. The deposition run may then be repeatedwith first pin mask 700 in place to correct the error determined by thetest run results. For example, in certain exemplary embodiments, firstpin mask 700 may be formed such that for each radial location along thesurface of substrate S to be coated, the percentage of the surface ofsubstrate S shadowed or occluded by first pin mask 700 is equal orapproximately equal to (e.g., within 10% or within 5% of) the percentagecoating thickness error determined by the test run for the opticalcoating, or for a particular layer of the coating at that radiallocation.

In certain exemplary embodiments, first pin mask 700 may be formed suchthat for each radial location along the surface of substrate S to becoated, the percentage of the surface of substrate S shadowed oroccluded by first pin mask 700 is proportional or approximatelyproportional to the percentage coating thickness error determined forthe optical coating or for a particular layer of the coating at thatradial location. For example, if the percentage coating thickness errorat a particular radial location is approximately 4%, the width W offirst pin mask 700 at that point may be approximately 4% ofcircumference of substrate S at that radial location.

It will be understood that the rate of deposition of a material onto asubstrate from a material source, e.g., from the target in magnetronsputtering, and therefore the degree of layer thickness error in theradial direction on the substrate may substantially change over theuseful life of the source. Thus, in certain embodiments it will beadvantageous to have the lateral width W of first pin mask 700substantially wider than required for correction of the initiallymeasured layer thickness error. The required total reduction in layerthickness can then be achieved by deploying the pin mask for less thanthe full time of the layer deposition. The amount or portion of alayer's deposition time that the mask is deployed can then be increasedor decreased over the life of the source, corresponding to depositionrate changes as the source material is used, its surface configurationchanges, and the resultant deposition rate changes. In this way the samepin mask can be used throughout the useful life of the source (or atleast for deposition of multiple layers during its useful life) byadjusting the amount of time it is deployed during deposition ofsuccessive layer. Thus, for example, in a case where the percentagecoating thickness error at a particular radial location is initiallyapproximately 4%, the lateral width W of first pin mask 700 at thatpoint may be approximately 8% of circumference of substrate S at thatradial location, and first pin mask 700 could be in position to shadowor occlude substrate S for half the deposition time. For deposition ofsubsequent layers as the source is used and the deposition rate changes,first pin mask 700 could be deployed in position to shadow or occludesubstrate S for correspondingly more or less than half the depositiontime.

It is to be appreciated that the design of first pin mask 700 may beconfigured such that its lateral width W at any radial locationcorresponds to the instantaneous rate of deposition, relative to theaverage weight, at that particular radial location. It is also to beappreciated that the design of first pin mask 700 may take intoconsideration the location at which it will be deployed relative to thelocations of the source/sources with respect to substrate S. Forexample, in a deposition chamber in which the source is not directlyopposite the substrate being coated but rather is offset from thecenterline (e.g., as in FIG. 9), the instantaneous deposition rate ontothe spinning substrate typically is substantially different at differentcircumferential locations. While spinning the substrate substantiallyovercomes this effect, stationary deployment of the pin mask results inthe degree of deposition rate adjustment being dependent on the locationof its deployment. Thus, for example, in the embodiment illustrated inFIG. 9, cathode assemblies 200A, 200B are oriented at angle E withrespect to substrate S. Thus, it will be understood from this disclosurethat the configuration of the pin mask, the amount of time the pin maskis deployed during the deposition of a layer (i.e. the portion orpercentage of the layer's deposition time), and the particular locationof the pin mask yield the total net adjustment of deposition thickness.

Another embodiment is shown in FIG. 13, in which a second pin mask 718is rotationally mounted above substrate S with a base 706A and spacedcircumferentially laterally from first pin mask 700 along substrate S.Second pin mask 718 optionally may have a lateral width WA that at someor all locations along its axial length is different than lateral widthW of the corresponding location of first pin mask 700 and, therefore,will shadow or occlude a different percentage of substrate S duringdeposition of a layer on substrate S. In the illustrated embodiment,lateral width WA of second pin mask 718 is less than lateral width W offirst pin mask 700 at corresponding points along the longitudinal axesof first pin mask 700 and second pin mask 718.

Thus, optionally first pin mask 700 and second pin mask 718 may be usedfor different layers of the deposited coating. First pin mask 700 may beused for some layers of the coating and not for others, e.g., first pinmask 700 may be used only for every other layer of an optical coating onsubstrate S, while second pin mask 718 can be used for the layersbetween the layers applied with first pin mask 700. It is to beappreciated that first pin mask 700 and second pin mask 718 can be usedin any sequence, and, in certain embodiments, can be usedsimultaneously.

Thus, first and second pin mask 700, 718 can be used in alternatingfashion to cover different percentages of substrate S to account fordifferent error amounts. As illustrated in FIG. 14, when first pin mask700 is in position over substrate S, second pin mask 718 may be pivotedabout base 106A such that it is not positioned over substrate S, atwhich point a coating may be sputtered from one or more of the cathodeassemblies onto substrate S to produce a particular layer. After thatparticular layer is deposited on substrate S with first pin mask 700,second pin mask 718 can be pivoted into position over substrate S, andfirst pin mask 700 may be pivoted away from substrate S (not shown), atwhich point a different layer may be deposited on substrate S.

Another embodiment is shown in FIG. 15, in which second pin mask 718 ispositioned behind a shutter 720 when it is rotated away from substrateS, such that no sputterable materials is deposited on second pin mask718 during a deposition process.

Those of ordinary skill in the art will recognize that the sputteringsystems and cathode assemblies disclosed herein present significanttechnical and commercial advantages. The preceding detailed descriptionof certain exemplary embodiments was not intended to limit the scope ofthe disclosure to merely those exemplary embodiments, but rather to beillustrative of such scope. Further, all examples, whether demarcated bythe terms “for example,” “such as,” “including,” “etc.” or otheritemizing terms, are meant to be non-limiting examples, unless otherwisestated or obvious from the context of the specification. Although thepresent invention has been described above in terms of certain exemplaryembodiments, it should be understood that other embodiments, other uses,alterations and modifications thereof will be apparent to those skilledin the art given the benefit of this disclosure, and that suchmodifications can be made and other features added without departingfrom the principles disclosed here. Thus, it will be appreciated thatvarious modifications and alterations will be apparent from thisdisclosure to those skilled in the art, without departing from thespirit and scope of the invention as set forth in the following claims.Also, it is intended that the embodiments described above beinterchangeable, e.g. one or more elements of any of the embodiments maybe interchanged with any of the elements of any other embodiments. It isalso intended that the following claims be read as covering all suchalterations and modifications as fall within the true spirit and scopeof the invention. It should be understood that the use of a singularindefinite or definite article (e.g., “a,” “an,” “the,” etc.) in thisdisclosure and in the following claims follows the traditional approachin patents of meaning “at least one” unless in a particular instance itis quite clear from context that the term is intended in that particularinstance to mean specifically one and only one. Likewise, the term“comprising” is open ended, not excluding additional items, features,components, etc.

1. A magnetron sputtering system comprising, in combination: a vacuumchamber; a substrate mount for mounting a substrate within the vacuumchamber; a plurality of cathode assemblies including a first set of oneor more cathode assemblies and a second set of one or more cathodeassemblies, and configured for sputtering, each cathode assemblycomprising: a target comprising sputterable material and having an atleast partially exposed planar sputtering surface, a target supportconfigured to support the target in the vacuum chamber and rotate thetarget relative to the vacuum chamber about a target axis, and amagnetic field source including a magnet array, the target beingpositioned between the magnet array and the substrate mount; and acathode assemblies controller assembly operative to actuate the firstset of cathode assemblies for sputtering the sputterable material of thefirst set of cathode assemblies without actuating the second set ofcathode assemblies, and to actuate the second set of cathode assembliesfor sputtering the sputterable material of the second set of cathodeassemblies without actuating the first set of cathode assemblies.
 2. Themagnetron sputtering system of claim 1, wherein the cathode assembliescontroller assembly comprises a timer operable to actuate at least oneset of cathode assemblies for sputtering for a period of time.
 3. Themagnetron sputtering system of claim 2, wherein the timer is operable toactuate the at least one set of cathode assemblies for sputtering for apredetermined period of time.
 4. The magnetron sputtering system ofclaim 2, wherein the timer is operable to actuate the at least one setof cathode assemblies for sputtering for a predetermined period of timedetermined in response to a value of an optical property of thesubstrate.
 5. The magnetron sputtering system of claim 1, wherein thefirst set includes two cathode assemblies and the second set includestwo cathode assemblies.
 6. The magnetron sputtering system of claim 1,wherein the first set includes one cathode assembly and the second setincludes two cathode assemblies.
 7. The magnetron sputtering system ofclaim 1, wherein the first set includes one cathode assembly and thesecond set includes one cathode assembly.
 8. The magnetron reactivesputtering system of claim 1, wherein the substrate is configured torotate at a speed of at least approximately 300 rpm.
 9. The magnetronsputtering system of claim 1, wherein the substrate is configured torotate at a speed between approximately 300 rpm and approximately 500rpm.
 10. The magnetron sputtering system of claim 1, wherein the cathodeassemblies are arranged in a confocal orientation about a central axis.11. The magnetron sputtering system of claim 1, wherein the substrate isconfigured to rotate about a central axis.
 12. The magnetron sputteringsystem of claim 10, wherein each target axis is oriented with respect tothe central axis at an angle of greater than 0 degrees and less than 90degrees.
 13. The magnetron sputtering system of claim 1, furthercomprising a first pin mask mounted in the vacuum chamber and configuredto mask a portion of a substrate mounted on the substrate mount.
 14. Themagnetron sputtering system of claim 13, wherein a lateral width of thefirst pin mask has a first value at its distal end, a second value at acentral point, and a third value at its proximal end, wherein the thirdvalue is larger than the first value and smaller than the second value.15. The magnetron sputtering system of claim 13, wherein the first pinmask is connected by an arm to a base that is pivotally mounted to thevacuum chamber.
 16. The magnetron sputtering system of claim 13, furthercomprising at least one additional pin mask.
 17. The magnetronsputtering system of claim 13, further comprising at least oneadditional pin mask having a profile different than a profile of thefirst pin mask, and laterally spaced from the first pin mask.
 18. Amagnetron sputtering system comprising, in combination: a vacuumchamber; a substrate rotatably mounted about a central axis within thevacuum chamber, and a plurality of cathode assemblies arranged in aconfocal orientation about the central axis, including a first set ofcathode assemblies and a second set of cathode assemblies, andconfigured for reactive sputtering, each cathode assembly comprising: atarget comprising sputterable material having an at least partiallyexposed planar sputtering surface, a target support configured tosupport the target in the vacuum chamber and rotate the target relativeto the vacuum chamber about a target axis, and a magnetic field sourceincluding a magnet array, the target being positioned between the magnetarray and the substrate, wherein the plurality of cathode assemblies isconfigured such that when the first set of cathode assemblies isoperational the second set of cathode assemblies is idle, and when thesecond set of cathode assemblies is operational the first set of cathodeassemblies is idle.
 19. The magnetron sputtering system of claim 18,further comprising a cathode assemblies controller assembly operative toactuate the first set of cathode assemblies and the second set ofcathode assemblies.
 20. The magnetron sputtering system of claim 19,wherein the cathode assemblies controller assembly comprises a timeroperable to control operation of the first set of cathode assemblies andthe second set of cathode assemblies.
 21. The magnetron sputteringsystem of claim 18, wherein the first set includes two cathodeassemblies and the second set includes two cathode assemblies.
 22. Themagnetron sputtering system of claim 18, wherein the first set includesone cathode assembly and the second set includes two cathode assemblies.23. The magnetron sputtering system of claim 18, wherein the first setincludes one cathode assembly and the second set includes one cathodeassembly.
 24. The magnetron sputtering system of claim 18, wherein thesubstrate is configured to rotate at a speed of at least approximately300 rpm.
 25. The magnetron sputtering system of claim 18, wherein thesubstrate is configured to rotate at a speed between approximately 300rpm and approximately 500 rpm.
 26. The magnetron sputtering system ofclaim 18, wherein each target axis is oriented with respect to thecentral axis at an angle of greater than 0 degrees and less than 90degrees.
 27. A magnetron sputtering system comprising, in combination: avacuum chamber; a substrate rotatably mounted about a central axiswithin the vacuum chamber and configured to rotate at a speed of betweenapproximately 300 rpm and approximately 500 rpm; a plurality of cathodeassemblies arranged in a confocal orientation about the central axis,including a first set of two cathode assemblies and a second set of twocathode assemblies, and configured for reactive sputtering, each cathodeassembly comprising: a target comprising sputterable material having anat least partially exposed planar sputtering surface, a target supportconfigured to support the target in the vacuum chamber and rotate thetarget relative to the vacuum chamber about a target axis, each targetaxis being oriented with respect to the central axis at an angle ofgreater than 0 degrees and less than 90 degrees; and a magnetic fieldsource including a magnet array, the target being positioned between themagnet array and the substrate; and a timer to control operation of thefirst set of cathode assemblies and the second set of cathode assembliessuch that when the first set of cathode assemblies is operational thesecond set of cathode assemblies is idle, and when the second set ofcathode assemblies is operational the first set of cathode assemblies isidle.